Vacuum coating system comprising a transport unit for transporting substrates

ABSTRACT

A vacuum coating unit with a transport device for transporting substrates in a transport direction, comprises at least one first endless conveyor running in the transport direction and having a conveyor device guided around at least two deflection rollers. The conveyor device is located at a distance from a guide device extending in the transport direction parallel to the conveyor device of the first endless conveyor in such a way that the substrates can be introduced into the gap between the conveyor device and the guide device and can be moved in the transport direction by the displacement of the conveyor device.

A vacuum coating unit with a transport device for transport of substrates in a transport direction is described below.

The described transport device is suitable for moving substrates through a vacuum coating unit in order to coat them, etch them or treat them in vacuum in some other way. Such vacuum coating units typically have lock chambers as well as a vacuum chamber arranged between the lock chambers, which can be divided into compartments with different functions, for example, pump compartments and process compartments.

During transport through the vacuum chamber the substrates can be rotated in one embodiment of the described transport device around their own axis. In another embodiment the rotation speed of the substrates can be chosen independently of the transport speed of the substrates in the transport device. Several transport devices of the described type can be arranged one behind the other in the transport direction so that the substrates being transported are transferred without interruption from one transport device to the transport device arranged behind it. Transport devices of the described type can be arranged next to each other, viewed in the transport direction, so that elongated substrates, for example, tubes, can be brought into effective connection with each of the ends with one of the two transport devices.

Substrates can be fed grouped in the transport device. Ordinary, temperature-sensitive bearings can be dispensed with so that the transport device can also be used for transport of substrates through high-temperature areas of a vacuum coating unit. In another embodiment defects of the transport device can be automatically recognized. An embodiment with substrate holders permits transport of different types of substrates without modification of the transport device.

A vacuum coating unit with a transport device for transport of substrates in a transport direction includes at least one first endless conveyor arranged running in the transport direction with an endless conveyor device guided around at least two return pulleys, which is arranged with a spacing to a guide device arranged running parallel to the conveyor device of the first endless conveyor in the transport direction so that the substrates can be introduced into the spacing between the conveyor device and the first endless conveyor and the guide device and moved by movement of the conveyor device in the first endless conveyor in the transport direction.

Endless conveyor according to the present teaching is to be understood to mean a device that has an endless conveyor device gathered around at least two return pulleys. The conveyor device of the endless conveyor can be an endless cable, for example, an endless belt with any cross section (circle, trapezoid, etc.), an endless belt (belt with a flat rectangular cross section) or an endless chain. The conveyor device can be designed as a stainless steel cable for use in high-temperature areas of the vacuum coating unit. An endless conveyor of the mentioned type can include several conveyor devices, for example, two endless stainless steel cables guided over the same return pulleys. The stability of the endless conveyor can be increased on this account, on the one hand, and its reliability improved, on the other, since the conveyor device is designed redundant and on failure of one conveyor device the second conveyor device is still available.

In one embodiment two of the described transport devices are arranged parallel and next to each other viewed in the transport direction in the vacuum chamber of a vacuum coating unit. The conveyor devices of the endless conveyor of the two transport devices in one variant are an endless steel cable and the guide devices are rails arranged parallel to the steel cable of the corresponding endless conveyor with a spacing, the distance between the steel cable and the rail being chosen so that the substrates being transported or the receiving devices provided to receive the substrates can be introduced at this spacing.

The substrates can be tubes to be coated. Each of these tubes is arranged across the transport direction, specifically so that each end of a tube lies at a spacing between the steel cable and the rail of one of the two endless conveyors. In an example of a variant the distance between the two transport devices arranged next to each other, i.e., their spacing across the transport direction, is adjustable. Because of this it is possible to transport elongated substrates of different length through the vacuum chamber of the vacuum coating unit.

If the endless conveyors are placed in operation, the sections of the steel cables of the two transport devices facing the rails are moved relative to the corresponding rails. Because of this the two ends of the tubes that are clamped between a steel cable and a rail are placed in rotational movements so that the tube rolls on the two rails and in this way the tube is transported in the transport device through the vacuum coating unit. The tubular substrate is simultaneously rotated around this longitudinal axis during transport through the vacuum chamber so that uniform coating on all sides can be achieved. Instead of a rail of similar static guide device, the guide device of each transport device can also be a second endless conveyor arranged with a spacing to the first endless conveyor so that the transport device includes at least one pair of endless conveyors.

In one embodiment the distance between the conveyor device and the guide device is adjustable so that the transport device can be adapted for use with different substrates. In another embodiment receiving devices to accommodate the substrate are provided. Such receiving devices can have, for example, a first, conveyor-specific cylindrical end whose diameter is chosen so that it can be introduced into the spacing between the conveyor device and the guide device, and a second substrate-specific end, configured so that it can be connected to a special substrate. For the case just mentioned, in which the substrates are tubes, the substrate-specific end could be cylindrical, the diameter being chosen so that it corresponds to the inside diameter of the tube. The substrate-specific end could also be noncylindrical, for example, have a square cross section or be provided with a clamping device.

Another embodiment proposes that the guide device is also an endless conveyor so that each transport device includes at least one pair of endless conveyors. In this case a first endless conveyor and a second endless conveyor are arranged running parallel to each other at a spacing in which the spacing between them corresponds to the diameter of the substrates being transported or to the conveyor-specific cylindrical end of a receiving device or in which the spacing between the first endless conveyor and the second endless conveyor of a transport device is adjustable. It can also be prescribed that the two first and second endless conveyors arranged at a spacing to each other of a transport device be controllable independently of each other. Through this embodiment the rotational speed of the substrate can be chosen independently of the translatory transport speed through the vacuum chamber.

For example, depending on the speed difference of the two endless conveyors it is possible to have the substrates rotate forward or backward. In the same manner it is possible in this embodiment to transport the substrates without rotation by operating the two endless conveyors at the same speed. It is also possible to place the substrates in rotation without moving them in the transport device. Moreover, the ratio of rotatory and translatory movement of the substrates along the transport path can be dynamically varied, in which the first and second endless conveyors of a transport device are driven accordingly.

For example, it is therefore possible to move substrates through the lock areas or so-called pump compartments that serve to maintain the process vacuum and vacuum separation between adjacent process compartments in purely translatory fashion, i.e., without a rotatory component, while the substrates are moved in the process compartment stationary with purely rotatory movement, i.e., without a translatory component in order to achieve uniform coating on all sides. By arranging several equivalent transport devices one behind the other it is possible to temporarily store subsequent substrates by stopping a first transport device in a buffer zone, while the substrates situated ahead in a second transport device are coated in a process compartment, etched or treated in some other way. After completion of treatment the substrates can be removed from the process compartment and the following substrates moved from the buffer zone and into the process compartment.

It can also be proposed that the conveyor devices of the two endless conveyors or transport device are deflected at several sites so that the substrates on their path through the vacuum chamber are moved up and down along the transport device. With this embodiment good frictional engagement between the conveyor devices and the substrates is ensured over the entire length of the endless conveyors. Deflection of the conveyor devices can be produced, for example, by firmly arranged or elastically mounted pressure rollers, which are arranged along the transport direction in alternating arrangement so that they deflect the conveyor device of an endless conveyor in a direction toward the conveyor device of the other endless conveyor. Because of this the conveyor devices of the two endless conveyors of a transport device initially run with a spacing that is less than the diameter of the substrates or the receiving devices. If the substrate or the receiving devices are introduced into the spacing and transported between the conveyor devices, the distance between the two conveyor devices is widened by the substrate or receiving devices to the necessary spacing. The pressure rollers arranged on both sides in alternation force a deflection of the substrate or receiving device so that the substrate or receiving device is moved back and forth in alternation during movement along the transport direction across the transport direction.

In the example just described in which two pairs of endless conveyors are arranged so that one end of a substrate can be introduced into the spacing of each pair of endless conveyors of the transport device, this embodiment produces an improvement in frictional engagement between the substrate and the two conveyor devices and at the same time alternating up and down movement of the substrate during transport through the vacuum chamber along the transport device.

When two or more transport devices are arranged one behind the other in the transport direction it can be provided that the conveyor devices of adjacent endless conveyors overlap so that one return pulley each of the two endless conveyors are mounted to rotate so that they have a common axis of rotation. In a modification a common return pulley can be provided, designed so that it simultaneously acts as return pulley for two endless conveyors. Substrates can be transferred on this account from a first transport device to a second transport device arranged behind it.

To recognize emergencies it can be prescribed that a monitoring device be arranged on at least one return pulley. Such a monitoring device can include two contact elements, one of which is mounted on the return pulley. The other contact element is arranged fixed in the vicinity of the return pulley so that during each revolution of the return pulley contact between the two contact elements occurs. As soon as the return pulley no longer rotates, for example, because the conveyor is torn, the absence of contact between the two contact elements can be recognized.

In another embodiment a transport cart is provided to accommodate the substrates, which has a number of receptacles. Such a transport cart can have a frame, for example, in which upward open recesses are provided in two opposite cross arms of the frame at uniform spacings, in which one end of a substrate or receiving device can be inserted. The transport cart can have wheels in order to facilitate its transport through the vacuum chamber. The transport cart can also have its own drive device.

The transport device can be designed so that the substrate receptacles are arranged at the same height level as the spacing between the conveyor device and the guide device of a transport device arranged in the interior of the vacuum chamber of the vacuum coating unit. Because of this the substrates of the receiving devices can be introduced without additional expedients into the spacing between the conveyor device and the guide device and in this way brought into effective connection with the transport device when the transport cart equipped with the substrates is introduced to the vacuum chamber.

The transport cart can be moved already by the effect of the substrates or receiving devices moved by the transport device on the substrate receptacles of the transport cart itself in the transport direction as soon as the substrates or receiving devices are moved by the transport device forward. When the transport cart has its own drive device, this can be driven so that the transport cart is moved by the action of the drive device synchronously with the movement of the substrates in the transport device through the vacuum chamber.

The described transport device is further explained below by means of practical examples and corresponding drawings. In the drawings

FIG. 1 shows a transport device with a static guide device,

FIG. 2 shows a transport device with two endless conveyors,

FIG. 3 shows a transport device with rigidly mounted pressure rollers,

FIG. 4 shows a transport device with elastically mounted pressure rollers,

FIG. 5 shows two transport devices arranged one behind the other in the transport direction,

FIG. 6 shows a transport cart,

FIG. 7 shows a receiving device for a tubular substrate,

FIG. 8 shows a monitoring device.

The practical example in FIG. 1 is a transport device with an endless conveyor and a static guide device arranged at a spacing 41 to it. The endless conveyor includes two return pulleys 11, 12, one return pulley of which is a drivable drive roller 11, as well as a conveyor device 2 in the form of an endless stainless steel cable. The static guide device is a rail 3 installed fixed within the vacuum chamber of the vacuum coating unit. In the practical example tubular substrates 51, which are arranged across the transport direction 42, are transported through the vacuum chamber. For this purpose the tubular substrates 51 are initially introduced into the spacing 41 between the stainless steel cable 2 and rail 3.

The spacing 41 is chosen so that the tubular substrates 51 are securely held between the stainless steel cable 2 and the rail 3. The drivable return pulley 11 is placed in movement in the direction of rotation shown by arrow 13. Because of the coupling between the two return pulleys 11, 12 caused by the stainless steel cable 2 the second return pulley 12 is also placed in movement in the direction of rotation shown by arrow 13. Because of friction between the stainless steel cable 2 and the tubular substrates 51 they are placed in rotation in the direction of rotation shown by arrow 52. The tubular substrates 51 therefore roll on rail 3 so that they are moved in a linear movement through the vacuum chamber in the transport device 42.

The transport device with a first endless conveyor and a second endless conveyor arranged parallel to it with a spacing 41, which acts as a guide device, as shown in FIG. 2. Both endless conveyors include two return pulleys 11, 12, one return pulley 11 of which is drivable. The driven return pulleys 11 of the two endless conveyors are controllable separately independently of each other. In the practical example the upper endless conveyor is driven more quickly than the lower endless conveyor, as indicated by the arrows 13 of different length, which show the direction of rotation at rotational speed of the return pulleys 11, 12.

The tubular substrates 51 arranged between the two endless conveyors are moved by the movements of conveyor device 2 of both endless conveyors in the transport direction indicated by arrow 42. At the same time the tubular substrates 51 because of the speed difference between the two endless conveyors are placed in rotation indicated by arrow 52. If the upper endless conveyor would be driven more slowly than the lower endless conveyor, the tubular substrates 51 would rotate in the opposite direction of rotation. In the practical example both endless conveyors are driven so that the part of the corresponding conveyor device 2 in contact with the tubular substrates 51 is moved in the transport direction 42. However, it should be mentioned that operational types are also possible in which one of the endless conveyors is driven in the opposite direction. The substrates 51 are moved in the transport direction 42 as long as the speed of this endless conveyor is smaller than the speed of the other endless conveyor.

In the transport device in FIG. 3 two endless conveyors are arranged in a spacing 41 to each other, which corresponds to the diameter of the tubular substrates 51. The spacing between the conveyor devices 2 between the return pulleys 11, 12 of the endless conveyors is reduced by several pressure rollers 61 which are installed fixed, i.e., rigidly. The pressure rollers 61 are arranged in alternation on the conveyor devices 2 of both endless conveyors so that the substrates 51 are moved upward and downward during movement through the gap 41 existing between conveyor devices 2 when they pass by the pressure roller 61.

The frictional engagement of the tubular substrates 51 with the two conveyor devices 2 is reinforced by the pressure roller 61 and the reduced spacing 41 of the two conveyor devices 2 relative to each other. The rotational speed indicated by arrow 13 of the return pulleys 11, 12 is equally large in the endless conveyors so that the tubular substrates 51 are laced in rotation. In order to keep the tension of the conveyor devices 2 of both endless conveyors constant, it is useful in this practical example to mount at least one of the return pulleys 11, 12 of each endless conveyor elastically.

The practical example in FIG. 4 differs from the one just described in that the pressure rollers 61 are elastically mounted on spring 62 so that the tension of the conveyor devices 2 of both endless conveyors is kept constant. The rotational speed of return pulleys 11, 12 of both endless conveyors indicated by arrows 13 is different so that the tubular substrates 51 are placed in rotation indicated by arrow 52.

Two equivalent transport devices are arranged one behind the other in FIG. 5. Each transport device again consists of an upper and lower endless conveyor. The areas of effect of the endless conveyors arranged one behind the other overlap in the area of the transition between them. For this purpose the conveyor devices 2 of the consecutive endless conveyors are passed over a common return pulley 14. As an alternative, separate return pulleys could be provided in this area. The separate return pulleys, however, could have a common axis of rotation. The separate return pulleys could be mounted on the same axle on this account.

The conveyor device 2 of each endless conveyor in the practical example is passed over a total of six return pulleys, two return pulleys 12 ensuring that contact of the conveyor device with the tubular substrates 51 or receiving devices for substrates 51 is produced, one return pulley of which is a common return pulley 14 above endless conveyors, two tension rollers 15 to maintain the tension in the conveyor device and two other return pulleys 11, 12, one drive roller of which 11 is drivable, which are responsible for reversal of the conveyor device 2.

A transport cart is shown in FIG. 6 which is designed to accommodate a number of substrates 51. For this purpose the transport cart has a frame with two longitudinal cross arms 71, each of which is provided with a number of substrate receptacles 72 which are designed as upward open recesses. The recesses 72 are designed so that receiving devices can be inserted into the recesses 72 to receive elongated substrates 51. Additional supports for the receiving devices are not provided.

The transport cart often has four wheels 73. The transport cart can be equipped outside of the vacuum coating unit with the substrates 51 to be treated in the vacuum and then introduced to the interior of the vacuum chamber through a lock. For this purpose ten elongated substrates 51 are either directly inserted with each end into one of two oppositely arranged substrate receptacles 72 corresponding to the number of substrates receptacles 72 arranged in pairs or connected on each end to a receiving device and then inserted into the transport cart so that each receiving device is supported on a substrate receptacle 72.

A receiving device suitable for this purpose is shown as an example in FIG. 7. In the practical example the receiving device is a rotationally symmetric part having several sections. The conveyor-specific end 81 is cylindrical and provided to extend beyond the longitudinal cross arm 71 of a transport cart and to enter into effective connection with the conveyor device 2 of an endless conveyor and a guide device. The substrate-specific end 84 is also cylindrical and designed to be inserted into the end of a tubular substrate 51.

Between the conveyor-specific end 81 and the substrate-specific end 84 there is a support section 82 with which the receiving device can be inserted into the substrate receptacle 72 of the transport cart. Between the support section 82 and the substrate-specific end 84 a stop 83 is arranged, which bounds the support section 82 on the one side and ensures a defined spacing between the end of the tubular substrate 51 and the support section 82, on the other side.

FIG. 8 shows a monitoring device for recognition of defects of an endless conveyor. A return pulley 12 is mounted to rotate on a bearing block 91. The return pulley 12 has a first contact element 92 on its side facing bearing block 91, which in the practical example is a spring steel sheet mounted on the deflection role. Electrically insulated from the bearing block 91 and therefore from the return pulley 12 a second contact element 93 is fixed on the bearing block 91. The second contact element 93 is designed as a flexible steel pin in the practical example. The flexibility is achieved by the fact that this steel pin 93 is a piece of stainless steel cable pressed into a mount.

If the endless conveyor is placed in operation, the return pulley 12 begins to rotate. During each revolution the spring steel plate 92 passes by the flexible steel pin 93 once. Contact between the spring steel plate 92 and the flexible steel pin 93 then occurs. In this way the two contact elements 92, 93 form a simple mechanical switch which closes a circuit on contact of the contact elements 92, 93. If no switching process is recorded, despite the endless conveyor being engaged, this means that the return pulley 12 is no longer rotating, from which it can be concluded that the conveyor device 2 of the endless conveyor is defective. The described monitoring device is robust, can withstand high surrounding temperatures and is insensitive to possibly undesired coating of the contact elements 92, 93, since these automatically mutually clean each other on each revolution.

LIST OF REFERENCE NUMBERS

-   11 Drive roller -   12 Return pulley -   13 Direction of rotation of drive roller or return pulley -   14 Common return pulley -   15 Tension roller -   2 Conveyor device -   3 Rail -   41 Spacing -   42 Transport device -   51 Substrate -   52 Direction of rotation of substrate -   61 Pressure roller -   62 Spring -   71 Longitudinal cross arm -   72 Substrate receptacle -   73 Wheel -   81 Conveyor-specific end -   82 Support section -   83 Stop -   84 Substrate-specific end -   91 Bearing block -   92 First contact element -   93 Second contact element 

1. Vacuum coating unit with a transport device for transport of substrates in a transport direction, comprising at least one first endless conveyor arranged running in the transport direction, the first endless conveyor including an endless conveyor device guided around at least two return pulleys, the conveyor device being arranged with a spacing to a guide device arranged parallel to the conveyor device of the first endless conveyor in the transport direction so that the substrates are introduced into the spacing between the conveyor device of the first endless conveyor and the guide device and are moved by movement of the conveyor device of the first endless conveyor in the transport direction.
 2. Vacuum coating unit according to claim 1, wherein the guide device comprises a second endless conveyor.
 3. Vacuum coating unit according to claim 2, wherein the first endless conveyor and the second endless conveyor are controlled independently of each other.
 4. Vacuum coating unit according to claim 2, wherein at least one conveyor device of the first and second endless conveyors includes at least one endless steel cable.
 5. Vacuum coating unit according to claim 2, wherein at least one conveyor device of the first and second endless conveyors includes at least two equivalent endless steel cables.
 6. Vacuum coating unit according to claim 1, wherein the conveyor device includes at least one flexible endless belt.
 7. Vacuum coating unit according to claim 2, wherein the conveyor device of the first endless conveyor and a conveyor device of the second endless conveyor are deflected viewed in the transport direction with alternating direction of rotation across the transport direction.
 8. Vacuum coating unit according to claim 1, wherein at least two endless conveyors are arranged one behind an other in the transport direction, a rear return pulley of the first endless conveyor and a front return pulley of a second endless conveyor having a common axis of rotation.
 9. Vacuum coating unit according to claim 8, wherein the rear return pulley of the first endless conveyor is simultaneously the front return pulley of the second endless conveyor.
 10. Vacuum coating unit according to claim 1, wherein a monitoring device to monitor movement of the return pulleys is provided on at least a first return pulley.
 11. Vacuum coating unit according to claim 10, wherein the monitoring device includes a first contact element arranged on the first return pulley and a second contact element arranged next to the first return pulley, the first and second contact elements being arranged relative to each other so that during each revolution of the first return pulley contact between the first contact element and the second contact element occurs.
 12. Vacuum coating unit according to claim 1, further comprising a transport cart to receive substrates, said cart having a number of substrate receptacles.
 13. Vacuum coating unit according to claim 12, wherein at least one of the substrate receptacles comprises is an upward open recess arranged in a longitudinal cross arm of the transport cart for receiving a substrate.
 14. Vacuum coating unit according to claim 12, wherein at least one of the substrate receptacles comprises an elongated hole arranged in a longitudinal cross arm of the transport cart for receiving a substrate.
 15. Vacuum coating unit according to claim 12, further comprising at least one substrate holders having one end connectable to a substrate and insertable into a substrate receptacle of the transport cart.
 16. Vacuum coating unit according to claim 15, wherein the at least one substrate holder has a support section for insertion into a substrate receptacle.
 17. Vacuum coating unit according to claim 12, wherein the transport cart is driven and controlled independently of the endless conveyor. 